I don't remember where I found the recipe, I think it was on pinterest several months ago.
My tweaks on this recipe are in bold.
I'm also making this as a salad, not as tacos. You could use low-carb tortillas, or gluten free or romaine hearts if you prefer the taco form.

Directions
1. In a large bowl, whisk together the vinegar, red pepper, and 2 teaspoons soy sauce. Add the cabbage and carrot and toss to combine. Let sit, tossing occasionally, for 15 minutes or until ready to serve.
2. Meanwhile, in a second bowl, combine the sugar, garlic, ginger, and remaining 2 tablespoons soy sauce. Add the beef and mix to combine.
3. Heat the oil in a large skillet over medium heat. Add the onion and cook, covered, stirring occasionally, until tender, 4 to 5 minutes. Add the beef mixture, increase the heat to medium-high, and cook, breaking it up with a spoon, until cooked through, 4 to 5 minutes.
4. Fill the tortillas with the beef and top with the slaw.